Building @babel/standalone fails on commonjs@15

[JLHwung]

• Rollup Plugin Name: commonjs@15.0.0, babel@5.2.0
• Rollup Version: 2.26.5
• Operating System (or Browser): macOS
• Node Version: 14.8.0
• Link to reproduction (⚠️ read below): https://github.com/JLHwung/babel/compare/rollup-2-plugin-commonjs-15

Rollup Config: https://github.com/JLHwung/babel/blob/95dc47882afbe98064f90420108f69b35b070f4a/Gulpfile.js#L123-L164

make bootstrap

Expected Behavior

Build all babel artifacts.

Actual Behavior

throws

Error: 'default' is not exported by rollupPluginBabelHelpers.js, imported by node_modules/chalk/templates.js

See https://github.com/JLHwung/babel/runs/1033102860#step:6:573 for the error logs.

Additional Information

I believe it is an integration issue between @rollup/plugin-babel and @rollup/plugin-commonjs: The plugin-babel serves a virtual file rollupPluginBabelHelpers.js via the load hook. It is am ESM moudle generated from @babel/core. So I guess what happens here is the babel helper is added to the chalk/templates (because of for-of helpers) but for some reason transformed as require when Rollup is processing. On reading https://github.com/rollup/plugins/tree/master/packages/commonjs#esmexternals, it seems that I should specify esmExternals, so I tried add to commonjs the following options.

esmExternals: ["\0rollupPluginBabelHelpers", "rollupPluginBabelHelpers"]

But the build still fails. Even in the end esmExternals works for this virtual file, it feel like a hack and I hope it can be processed by @rollup/plugin-babel.

Another issue may be related: I tried downgraded commonjs@14 but our standalone test fails: https://github.com/babel/babel/runs/1033085554#step:10:128 I haven't investigate yet.

As a workaround we are pinning commonjs to 13: babel/babel#12010

[lukastaegert]

Would it be possible to boil this problem down to have a reproduction that only contains few files and as few plugins as possible and directly calls Rollup? esmExternals sounds like it does not apply here anyway because it only applies to files that are NOT bundled? Fiddling with requireReturnsDefault sounds like more of an option, but it is false by default meaning it should not cause issues here.

[JLHwung]

@lukastaegert Sorry for the late reply. Here is a reproduction repo: https://github.com/JLHwung/rollup-plugin-issue-557

It bails when a babel option sourceType: "unambiguous" is configured. So it involves how Babel play with @rollup/plugin-babel. I will see if there is any I can do on Babel side.

[lukastaegert]

Did you try version 15.1.0 of the commonjs plugin?

[JLHwung]

@lukastaegert The reproduction repo uses 15.1.0.

[stale]

Hey folks. This issue hasn't received any traction for 60 days, so we're going to close this for housekeeping. If this is still an ongoing issue, please do consider contributing a Pull Request to resolve it. Further discussion is always welcome even with the issue closed. If anything actionable is posted in the comments, we'll consider reopening it. ⓘ